The large-margin property is introduced by Sphereface [1]}, which defines a general function \(\psi (\theta )\)  to impose the angular margin between feature and weight vectors. After applying feature and weight normalization (\(\Vert W_{y_i}\Vert  = \Vert \mathbf {f}_i\Vert  = 1\) ), the loss function becomes
\(\mathcal {L}_{S} = -\frac{1}{n}\sum _{i=1}^n{log\frac{e^{\psi (\theta _{y_i})}}{e^{\psi (\theta _{y_i})} + \sum _{j=1,j\ne y_i}^{c}{e^{cos(\theta _{j})}}}},\) 
